23. Care for older people/ 22. Personality and experimental social psychology Older persons must cope with multiple uncertainties when making decisions about their health care. When selecting a substitute decision maker, a person must confront uncertainties about whether the person can be trusted to know and honor the person's wishes and whether the person can be a forceful advocate who can insist that these wishes are followed. The purpose of this study is to provide a preliminary test of uncertainty management theory. This newly-developed communication theory assumes that a) serious illnesses entail multiple uncertainties for patients, their families, and care providers; b) uncertainties will be managed rather than necessarily reduced; and c) preferred uncertainty management strategies are predictable based on psychological, social, and organizational factors. As a preliminary test of this theory, 240 older adults recruited from the Morgantown region will be randomly assigned to participate in one of three versions of a phone interview. Type of uncertainty will be manipulated by telling one group to select a substitute decision maker who can be trusted the most, a second group to select a decision maker who will be the most effective advocate, and a third group to select a decision maker (control group). After learning who is selected, persons will be asked questions to measure the importance of these uncertainties, willingness to designate this person as their medical power of attorney, confidence in the decision maker, and other factors. This design will allow us to test predictions about the associations between uncertainty and surrogate selection behavior. Results will make an immediate contribution to efforts to encourage older pers6ns to select and legally authorize appropriate surrogates. Beyond this, the study will provide support for the value of uncertainty management theory in explaining a wide range of health decisions that older persons are often asked to make.